Would this sub be good in a ported enclosure tuned at 20Hz?

  • Thread starter cameron paterson
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Verdinut

Verdinut

Audioholic General
Ratings
557 6 22
#2
First of all, the driver shown in the link you provided is not a subwoofer, it's an ordinary woofer.
According to the published Thiele/Small parameters, with that 18" woofer, you won't be able to obtain much output below 30 Hz if it even can reproduce such frequencies.
If you want to build your own sub, I would recommend that you verify the Dayton RSS390HO-4 subwoofer at Parts-Express if it is to be used for watching movies. If you intend to do serious music listening as well, then the Dayton RSS390HF-4 would be better. Parts-Express will also be in a good position to answer your questions and help you as Dayton and them is owned by the same people.
I am using three of the HF Series ones in my 3 front speaker cabinets with excellent results. The boxes have a net volume of 7.8 cf tuned at 16 Hz and I am getting an F3 at 20 Hz without any Eqing.
Pictures of my equipment: https://forums.audioholics.com/forums/threads/my-7-channel-system.111234/
 
Last edited:
TLS Guy

TLS Guy

Audioholic Slumlord
Ratings
7,253 17 24
#3
http://reaudio.com/products/woofers_xxx.php

If you look at the second ported box it says 6.9ft3 but says it only needs a vent that is 10" wide x 3" long. That sounds super small! Could I tune this sub at 20Hz?
We have tried to explain this to you before, but you don't get it. You DON NOT get to choose the tuning frequency. The T/S parameters of the driver do. You do not understand at all how to model a driver.

Now for any driver there is an optimal box where the sound quality will be optimal. This f3 and tuning is always higher than an extended bass alignment that does not usually sound as good. The fs of the driver is a big determinant of the bass extension. Usually the optimal box will tune a little higher than fs. Be very suspicious of alignments with F3 a little below fs.

So in answer to your question no, that driver will not get to an f3 of 20 Hz. The fs is 29Hz. Now the smaller of the two boxes will be better. However the driver is not promising as it has a nasty peaked response in a ported alignment.

Now port size. This is another thing you do not understand.

The air in the port is the equivalent of the weight on an oscillating spring.
What you have to pay attention to is keeping the vent air velocity to around 20 m/sec which is about 60 ft/sec. If the vent is too small then vent air velocity is too high and the vent will be noisy. So you keep the port NO larger than you have to, to meet this criteria. If you make the port bigger it will be unnecessarily long and therefore invite port resonances.

Essentially when you pick a driver, it determines how it needs to be loaded and aligned. You have extremely limited choice in the matter. Your job is to find how to optimize the driver, NOT impose your preconceived notions on the driver. This last point is what I really want you to understand, so we do not keep getting these nonsensical posts from you.
 
Swerd

Swerd

Audioholic Spartan
Ratings
4,386 10 2
#4
I agree completely with TLS Guy. Tuning frequency choices are made when you select a woofer. Its T/S parameters will tell you what is possible.

You may have software that allows cabinet designing for woofers, but you still have to learn what makes for a good or bad design. Buy or borrow a copy of Speaker Building 201 by Ray Alden. Read and understand the first three chapters.
 
Eng-399

Eng-399

Audioholic Intern
Ratings
22
#6
Why don’t you guys model the driver then in winisd. The driver’s ts perms doesn’t show bl in it perms or else I would do it.
 
TLS Guy

TLS Guy

Audioholic Slumlord
Ratings
7,253 17 24
#7
Why don’t you guys model the driver then in winisd. The driver’s ts perms doesn’t show bl in it perms or else I would do it.
Because if you look on their site those drivers have all been modeled in Box Pro twice, as optimal box and an extended bass alignment. Box Pro is a very good modeling program.
 

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